Translate project to English

[DrGekoz]

Summary

Localizes the entire project to English: code comments, docstrings, user-facing API response messages, configuration defaults, documentation (README.md, AGENTS.md), shell scripts, and test files.

Changes

• API response messages now return English: account not found (404), unauthorized (401), and the service.py business-failure reasons (auth cookie has expired..., fetch failed: ..., this account has no OpenCode Go subscription, failed to parse usage data from the page...).
• Config defaults localized for consistency:
  • fetch.locale default zh -> en
  • response.data_template default words translated to Rolling / Weekly / Monthly
• Docs / scripts / config example fully translated.
• Tests updated to match the translated messages; all 58 pass (uv run pytest).

Notes

• The parser remains locale-independent by design (it locates usage items by data-slot structure, not label text), so pages served in any locale still parse correctly.
• The test fixture DOM_HTML_EN covers a non-default-locale page; the Chinese invalid-account-ID test case ("中文") is kept intentionally to verify such IDs are rejected.

[andywang425]

Thanks for your translation work! My English is not good so i use deepseek to help me review your PR and write this review :)

A few adjustments before this can merge:

Keep English for all user- and deployer-facing strings (no change needed)

This service must be self-hosted (it carries per-account auth cookies), so every operator is also a user. English is correct for: the API response messages (account not found 404, unauthorized 401, the service.py business reasons), the default response.data_template (Rolling / Weekly / Monthly), the pyproject.toml description, the ConfigError messages in config.py, the CLI error prefix in cli.py, the gen-cert.sh output and usage text, and the comments in config.example.toml.

Restore Chinese for maintainer-facing code comments

The project is maintained in Chinese by me (with limited English proficiency :( ), so please revert the following to Chinese (the original text is preserved in git history on master):

• Code comments and docstrings across all modules, including the test files.
• AGENTS.md.

README: bilingual instead of fully English

The fully-English README drops the existing Chinese documentation, which this project wants to keep. Please:

• Keep the translated README.md in English as the default entry.
• Add a Chinese version as README.zh-CN.md (restore the pre-PR Chinese README from git history rather than re-translating).
• Add a language-switch link at the top of README.md, e.g. English | 简体中文.

DOM fixture: actually exercise a non-default locale

The PR description says DOM_HTML_EN covers a non-default-locale page, but since this PR also changes the default fetch.locale from zh to en, English is now the default — so both DOM_HTML and DOM_HTML_EN end up English and the non-default-locale path is no longer tested. That coverage is what backs the parser's "locale-independent" claim, so please make one fixture a genuine non-English page again — e.g. restore DOM_HTML to Chinese (滚动用量 / 重置于 5 小时 0 分钟) and keep DOM_HTML_EN for English, updating the corresponding assertions in tests/test_parser.py (e.g. reset_text "5 小时 0 分钟").

Thanks again, happy to answer any questions.